Holder block system and methods for metal casting

ABSTRACT

A holder block system suitable for producing metal castings. The holder block system includes a holder block primary mold that has one or more cavities that accept a sub-mold that incorporates the features of the part to be cast, wherein the sub-mold can be produced utilizing 3-D printing. Methods of preparing holder block patterns and cast objects are with the holder block system disclosed.

FIELD OF THE INVENTION

The present invention relates to a holder block system suitable forproducing metal castings. The holder block system includes a holderblock primary mold that has one or more cavities that accept a sub-moldthat incorporates the features of the part to be cast, wherein thesub-mold can be produced utilizing 3-D printing. Methods of preparingholder block patterns and cast objects with the holder block system aredisclosed.

BACKGROUND OF THE INVENTION

Sand casting is a popular method utilized to produce metal componentshaving various geometries. Sand molds that are destroyed in order toremove the cast part are utilized.

With the advent of 3-D printing, 3-D printers have been utilized toprint molds suitable for use in sand casting. However, producing castmaterials with 3-D printed molds can be quite expensive, at least inpart because of the potentially large amount of printing material andlong time needed to produce a mold and in some cases a large print sizerequired. 3-D print materials are also relatively expensive.

SUMMARY OF THE INVENTION

In view of the above, a problem of the invention is to provide rapidlyproducible, yet cost effective metal cast components.

The problem of the invention is solved by the holder block system of thepresent invention which includes a holder block primary mold, preferablyformed by traditional, inexpensive sand molding methods, that includesone or more cavities that accept a sub-mold that includes the featuresof the component or part to be cast, wherein the sub-mold is producedutilizing 3-D printing.

Yet another object of the present invention is to provide a holder blockprimary mold that includes one or more cavities, with a sprue, well,runner and ingate.

Still another object of the present invention is to provide a unitary,single piece, 3-D printed sub-mold that is free of a separate core.

A further object of the present invention is to provide a holder blocksystem including a primary mold including a cavity which contains asub-mold, wherein the compositions of the mold and sub-mold are the sameor different. In a preferred embodiment, the materials of the primarymold and sub-mold are different, with the holder block primary moldfabricated by a traditional no-bake or a similar sand-molding process.Utilizing a traditional primary construction, mold preparation time isrelatively short and also is relatively inexpensive. The sub-moldsprepared by 3-D printing take relatively longer time to prepare and alsorequire special materials.

Yet another object of the present invention is to provide a method forproviding a holder block system comprising the steps of providing aprimary mold having at least one cavity and one or more of a sprue,well, runner and ingate; providing a 3-D printed sub-mold including aninterior surface having a shape of an object to be molded; inserting thesub-mold into the cavity of the mold; and adding a molten metal to aportion of the mold such that a molten metal flows into the sub-moldfrom the mold.

Still another object of the present invention is to provide a sub-moldthat is formed as a single piece, utilizing 3-D printing, wherein thesub-mold is free of a cope and drag.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and other features andadvantages will become apparent by reading the detailed description ofthe invention, taken together with the drawings, wherein:

FIG. 1 illustrates one embodiment of holder block system which includesa sub-mold ready to be inserted into a holder block primary mold; and

FIGS. 2 a and 2 b illustrate a top view and a bottom view, respectively,of a cast part made with the holder block primary mold and the 3-Dprinted sub-mold shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

A holder block system is disclosed comprising a holder block patternincluding a primary mold that has one or more cavities that accept asub-mold that incorporates the features of a part to be cast. Theprimary mold does not contain any features of the part to be cast, in apreferred embodiment. Advantageously, the sub-mold is produced with a3-D printer. Methods for producing metal castings with the holder blocksystem of the present invention are disclosed.

Primary Mold Production

The holder block system of the present invention includes a holder blockpattern comprising a holder block primary mold. The primary mold has oneor more cavities that are designed to accept one or more sub-molds. Asillustrated in FIG. 1, the holder block system 10 includes a primarymold 20 and a sub-mold 40. Primary mold 20 includes a form such as aflask 22 into which a molding composition 24 is placed. Any suitablecomposition known to those of ordinary skill in the art can be utilized.Molding compositions typically comprise sand, e.g. silica sand (SiO₂),which is preferably mixed with a binder or other material that aids inmaintaining the shape of the mold cavity 26 and/or any other desiredfeatures. Sand is relatively inexpensive and resistant to thetemperatures at which metal parts are cast and molded. Various additivesthat can be utilized with the sand, include but are not limited to,various resins, clays, water, and oils.

The molding composition is added to the flask 22 and placed around apattern, which is preferably in the form of a replica of the externalshape of the sub-mold. The pattern can also include a gating system 28.In other embodiments the gating system is formed separately. The gatingsystem includes one or more of a sprue 29, well 30, runner 32 and ingate34, for example as shown in FIG. 1. Various types of molds can becreated, for example green sand molds, no-bake molds, air set molds, drysand molds, cold box molds, vacuum molds or the like.

In view of the use of a sub-mold, the holder block mold is free of anypart-specific features. Thus, the holder block pattern primary mold 20includes one or more generic cavity blocks or cavities. The genericcavity or cavities 26 created in the holder block mold 20 accepts asmaller sub-mold or several small sub-molds, each made to fit into thecavity. Thus, the holder block mold provides all the features necessaryfor casting a high-integrity part and at the same time, allows thesub-molds to incorporate only the features of the part to be cast.

Sub-molds

As indicated herein, the sub-mold is produced by 3-D printing. The outerdimensions of the sub-mold 40 are adapted to be placed in at least aportion of the cavity 26 of mold 20, for example as illustrated inFIG. 1. The sub-mold 40 includes an ingate 42 adapted to align withgating system 28 of mold 20 and thereby accept the molten metal into theinterior cavity of sub-mold 40.

Various techniques and procedures have been developed which utilize3-dimensional printers to form components such as molds, models andprototypes using 3-D design data. 3-D printers are available fromvarious sources, including, but not limited to, 3D Systems, Inc.; EOSGmbH; Prometal, a division of the Ex One Company; Stratasys, Inc.; and ZCorporation.

According to the present invention, a 3-D printer is utilized to print asand sub-mold directly onto a print bed. As known to those of ordinaryskill in the art, 3-D printing provides a process for making a3-dimensional object of virtually any shape from a digital model. 3-Dprinting utilizes an additive process where successive layers ofmaterial are laid down in different shapes. According to the presentinvention the sub-mold 40 includes a printed exterior surface 44. Theinterior surface of the sub-mold includes at least a negative image of acomponent to be cast. The 3-D printing process excels in creatingcomplex molds and eliminates entirely the need for cores. Thus, in oneembodiment, the holder block system of the present invention is free ofa core.

After the sub-mold 40 is formed, it is placed within the mold cavity 26such that the holder block pattern can be subsequently cast.

Pouring

After the holder block system 10 has been assembled, a desired alloycomposition is poured into the mold. Various molten materials,preferably metal as known to those of ordinary skill in the art can beutilized. Generally, molten metal is ladled or poured from a holdingcontainer into the sub-mold through the gating system of the baseprimary mold 20. A suitable amount of molten metal is poured in order tofill the entire cavity of the sub-mold 40 and preferably the gatingsystem 28.

Finishing

After the desired component has been cast in the holder block pattern 10of the present invention, conventional steps can be taken to produce afinished component. For example, the mold is opened after a suitablecooling time has elapsed. In order to remove the cast component from theholder block pattern, the sand-based molds are generally broken and thecasting removed therefrom. Excess material can be trimmed from thecasting through any suitable process such as cutting, sawing, trimmingor the like.

FIG. 2 illustrates a top view and a bottom view, respectively of thecast component formed utilizing the holder block mold 20 and sub-mold 40illustrated in FIG. 1. It is noted that the “FEF” logo plaque is theusable casting that was inside the 3-D printed sub-mold. The castingalso includes the sprue, fanned ingate and riser, all necessary toobtain a desirable plaque.

While in accordance with the patent statutes the best mode and preferredembodiment have been set forth, the scope of the invention is notlimited thereto, but rather by the scope of the attached claims.

What is claimed is:
 1. A holder block system, comprising: a primary moldcomprising a cavity; and a 3-D printed sub-mold located in the cavity,the sub-mold having an outer surface adapted to mate with at least aportion of the cavity, and wherein an interior surface of the sub-moldincludes at least one negative image of a component to be cast.
 2. Theholder block system according to claim 1, wherein the sub-mold is formedas a single piece.
 3. The holder block system according to claim 1,wherein the primary mold comprises a gating system, wherein the sub-moldincludes an ingate adapted to align with the gating system on theprimary mold and thereby accept a molten metal into an interior cavityof the sub-mold.
 4. The holder block system according to claim 3,wherein the sub-mold is free of a separate core and a cope and drag. 5.The holder block system according to claim 1, wherein the primary molddoes not contain any features of a part to be cast utilizing the holderblock system.
 6. The holder block system according to claim 1, whereinthe sub-mold is formed from a different material than the primary mold.7. The holder block system according to claim 1, wherein the primarymold comprises a flask and a molding composition located within theflask, with a cavity being present in the molding composition.
 8. Theholder block system according to claim 3, wherein the primary moldgating system comprises one or more of a sprue, well, and runner.
 9. Amethod for producing a holder block system, comprising the steps of:providing a primary mold having at least one cavity and one or more of asprue, well, runner and ingate; providing a 3-D printed sub-moldincluding an interior surface having a shape of an object to be molded;inserting the sub-mold into the at least one cavity of the primary moldto form the holder block system.
 10. The method according to claim 9,further including the step of forming the primary mold by adding amolding composition to a flask and incorporating a pattern into themolding composition in the form of the at least one cavity.
 11. Themethod according to claim 10, further including the step of forming agating system in the molding composition that includes one or more of asprue, well, runner, and end gate.
 12. The method according to claim 11,further including the step of forming an ingate on the sub-mold andaligning the ingate with the gating system of the primary mold.
 13. Themethod according to claim 12, wherein the primary mold is formed so thatit does not contain any features of a part to be cast with the holderblock pattern.
 14. A method for producing a metal casting, comprisingthe steps of: obtaining a primary mold having at least one cavity;obtaining a sub-mold including an interior surface having a shape of anobject to be cast, wherein the sub-mold is 3-D printed and has anexternal shape adapted to be placed in at least a portion of the cavityof the primary mold; inserting the sub-mold into the at least one cavityof the primary mold; and adding a molten metal to a portion of theprimary mold such that the molten metal flows from the primary mold intoa cavity of the sub-mold including the interior surface.
 15. The holderblock system according to claim 14, wherein the sub-mold is free of aseparate core and a cope and drag.
 16. The holder block system accordingto claim 15, wherein the primary mold comprises a gating system, whereinthe sub-mold includes an ingate aligned with the gating system on theprimary mold and thereby accept the molten metal into an interior cavityof the sub-mold.
 17. The holder block system according to claim 16,wherein the primary mold does not contain any features of a part to becast utilizing the holder block system.
 18. The holder block systemaccording to claim 17, wherein the sub-mold is formed as a single piece;and wherein the primary mold gating system comprises one or more of asprue, well, and runner.